I understand that rhyme is well established in Medieval Greek (and Latin) after the 11-12th centuries. But surely there are attested earlier cases before that. Do they go back to Koine? Maybe before it, even? What would be the earliest reasonable rhymes in late Koine?
The earliest example of rhyme in Greek that I was able to find is from Gorgias, who deliberately used rhyme in his rhetoric:
"In the fifth century BC the sophist Gorgias used such blatant rhyme effcts that the audience, anticipating the rhymes, shouted them out in advance..." Michael McKie
An example of Gorgias' use of rhyme is quoted in Plutarch's Lives, Cimon:
Κίμωνα τὰ χρήματα
κτᾶσθαι μὲν ὡς χρῷτο
χρῆσθαι δὲ ὡς τιμῷτο
(note: I arranged it in poetical form to show its parallel structure.)
"Cimon made money that he might spend it, and spent it that he might be honoured for it."